Bacterial Motion in a Noisy Medium

C.A. CONDAT; S.A. MENCHÓN; J. JÄCKLE

Buenos Aires

Congreso; XIV International Biophysics Congress; 2002

International Union for Pure and Applied Biophysics

Bacterial motion consists of two phases: approximately straight stretches ("runs") are separated by "tumbles". In a "tumble" the bacterium stops and begins a new run in an arbitrary direction. Small bacteria are strongly buffeted by Brownian forces that make rectilinear runs impossible. A model for bacterial motion is formulated in which the effects of fluctuational forces and torques on the run phase are taken into account by using coupled Langevin equations. An integrated description of the motion, including runs and tumbles, is the obtained by the use of convolution and Laplace transforms. The properties of the resulting velocity-velocity correlation function and of the mean square displacement are then studied. When looked over long times, the motion becomes diffusive; the properties of the resulting diffusion coefficient are discussed.